An anesthesia respirator with circulation of the breathing air and with control circuits for setting the anesthesia gas components to predetermined values has become known from DE 40 04 034 A1. The control circuits are designed essentially to maintain a quasi stationary operating state, i.e., the anesthetic gas components are maintained at previously set concentration values according to a control algorithm. To analyze the anesthesia components, an oxygen sensor, a carbon dioxide sensor, and an anesthetic sensor are arranged at different points of the breathing circuit. The anesthetic gas flows from a gas-metering unit for oxygen and laughing gas into the breathing circuit, wherein an inhalation anesthetic is also added to the breathing gas by means of an anesthetic-metering pump between the gas-metering unit and the breathing circuit. A control unit with integrated computing unit is the set point transducer for the gas-metering unit and the anesthetic-metering unit. The prior-art anesthesia respirator is supplied with gas from compressed gas cylinders or from a central gas supply system.
If the prior-art anesthesia respirator is operated from compressed gas cylinders, the duration of use in the case of mobile operation is limited by the capacity of the compressed gas cylinders carried with the anesthesia respirator. If is often difficult during mobile operation to refill a compressed gas cylinder on the site or to replace one with a full cylinder. This applies especially to the use of the apparatus under emergency conditions.
Chlorate candles, which burn off spontaneously after ignition and release oxygen due to the thermal decomposition of the chemical, have been known as oxygen sources. Such chlorate candles are used, e.g., to supply oxygen for passengers onboard airplanes. The passengers receive the oxygen via breathing masks, which are accommodated above the passenger seats in a container, which is automatically opened when the pressure drops in the passenger compartment. Such a device has been known from U.S. Pat. No. 3,981,300.